Gripper heads have become known in various embodiments in the state of the art. The gripper heads comprise a clamping device in which the end of a weft thread is clamped and inserted into the loom shed. The opening of the clamping device can, for example, be carried out via a control rail in the area of the cloth edge or fell, or magnetically. The DE 25 17 011 B1 and the DE 299 08 543 U1, which describe such gripper heads, are for use with a thread-shaped weft material, whereby the weft material is presented to the gripper head lying obliquely or sloping in order to be clamped between the clamping surfaces of the clamping device. The mentioned gripper heads are not suitable for band-shaped weft materials, because these can be damaged by the oblique clamping in the clamping device.
The U.S. Pat. No. 5,455,107 shows a gripper head with a clamping device, which is to be suitable also for band-shaped weft materials. The free end of the weft material is clamped in a clamp that is fixedly arranged on the weaving machine, and is presented to the gripper head by a feeder that is movable in the warp direction along the cloth edge. The weft material is presented to the gripper head at an angle, similarly like with the above described devices, so that it can lead to damages especially with weft bands that contain reinforcing fibers.
The WO 2006/075961 A1 shows an insertion element which is suitable for the insertion of a band-shaped weft material and comprises a comparatively wide clamping device, which can clamp a band-shaped weft material in a straight stretched condition. The insertion element can be embodied as a gripper head or also as a projectile. The weft band is inserted into the loom shed in a conventional manner by means of the insertion element, and is then conveyed to the interlacing point by means of two clamps which are arranged in the area of the cloth edges and which are movable in the warp direction. A damage of the weft material by a conventional weft beat-up is hereby avoided. In connection with an excess swinging or over-shooting of the insertion element beyond the provided transfer position, under certain circumstances it can lead to damages of the weft material.
Further documents that show gripper heads are the DE 6 45 465 A, the DE 25 41 990 A1 as well as the EP 20 37 023. However, none of the gripper heads shown here is suitable for inserting band-shaped weft materials with a larger width into a loom shed without damages.